Silver salt diffusion alkaline bath of trisodium phosphate and a polyalcohol

ABSTRACT

The modification of the silver salt diffusion process comprises exposure of a supported silver halide emulsion layer containing a photographic developer and development of the exposed layer with an alkaline Trisodiumphosphate bath while in contact with a nucleated image-receiving layer. The stability of the bath is improved by incorporating water-soluble aliphatic polyalcohols or polyamines.

United States Patent Liebe et al.

[ Feb. 29, 1972 SILVER SALT DIFFUSION ALKALINE BATH OF TRISODIUMPHOSPHATE AND A POLYALCOHOL Inventors: Werner Liebe; Harald vonRintelen, both of Leverkusen, Germany; Gerard Laurens Vanreusel, Hove;Camille Angelina Vandeputte, Mortsel, both of Belgium Assignee:Agia-Gevaert Aktiengesellschait, Leverkusen, Germany Filed: Feb. 9, 1970Appl. No.: 10,035

Foreign Application Priority Data Feb. 8, 1969 Germany ..P 19 06 296.5

US. Cl ..96/29 Int. Cl ..G03c 5/54 Field of Search ..96/29, 66, 95

[56] References Cited UNITED STATES PATENTS 3,189,449 6/1965 Yost..96/95 2,843,485 7/1958 Yutzy et al ..96/29 Primary ExaminerNorman G.Torchin Assistant Examiner.lohn L. Goodrow Atl0rney-Connolly and Hutz[57] ABSTRACT 2 Claims, No Drawings SILVER SALT DIFFUSION ALKALINE BATHOF TRISODIUM PHOSPHATE AND A POLYALCOHOL The invention relates to animprovement in the silver salt diffusion process, wherein thephotographic materials comprising at least one silver halide emulsionlayer which contains photographic developers are developed with analkaline bath.

French Pat. No. 879,995 describes the silver salt diffusion process forthe direct production of positives in which the unexposed, and henceundevelopable silver halide of a silver halide emulsion layer which hasbeen exposed to form an image is dissolved during development and isthen developed to give a positive image in another image receiving layerwhich is in close contact with the silver halide emulsion layer. Thedevelopment is carried out in the presence of development nuclei whichare incorporated in this layer. The terms negative and positive are hereused only in a relative sense, i.e., direct negatives can also beobtained from a negative original by the same process.

In the conventional silver salt diffusion process, the development bathsused have substantially the usual compositions, i.e., developersubstances in an alkaline aqueous solution. Owing to the sensitivity tooxidation of the developer substances, the lifetime of such developmentbaths is limited. To overcome this disadvantage, the silver saltdiffusion process has been modified so that the photographic developersubstance is added to at least one of the photographic layers of thematerial used, in particular to the silver halide emulsion layer. Whenusing such materials, a so-called activator bath is used for thedevelopment. This activator bath contains alkali as the main reagent, inaddition to the other conventional additives such as stabilizers, toningagents etc.

These activator baths usually contain trisodium phosphate as thealkaline substance because of its resistance to carbon dioxide. Theutility of trisodiumphosphate baths, however, is limited since trisodiumphosphate undergoes crystallization. Needle-shaped crystals of thissubstance are very easily deposited on the surface of the activator bathso that the conducting elements and applicator rollers in the processingapparatus as well as the photographic materials become contaminated.

lt is the object of the invention to provide activator baths which arestable for as long as possible and will not contaminate the apparatusand materials by crystallization of the substances contained in thebath.

We now have found a silver salt diffusion process for the production ofphotographic images by exposure of a photographic material whichcontains at least one supported silver halide emulsion layer whichemulsion layer contains one or more photographic developer substances,and development of this exposed material by treating it is an alkalinebath in contact with an image receiving layer which contains developmentnuclei, wherein the alkaline bath contains trisodium.

phosphate as alkaline substance and water-soluble aliphatic polyalcoholsor polyamines.

Aliphatic polyalcohols which contain three to six carbon atoms and atleast three hydroxyl groups are especially suitable. The following areexamples of suitable compounds of this type: glycol, glycerol, mannitol,sorbitol, sugars such as saccharose or glucose, dipropylene triamine andtriethylene tetramine. The alkaline baths of the present invention arereferred to hereinafter as activator baths.

The above mentioned substances are added to the activator baths inquantities of between 5 and 50 g. preferably between 15 and 30 g. perliter of bath liquid. When using sugars, it is advisable to usequantities at the lower end of the given range since at higherconcentrations the finished photographic material becomes sticky.

Mixtures of the polyalcohols or polyamines may, of course, also be used.If desired, this substance may be applied together with aliphatic aminoalcohols such as ethanolamine or diethanolamine. Glycerol or mannitol orsorbitol has proved to be particularly suitable.

The activator baths otherwise have the usual composition. The followingrecipe may be used as a general guide:

l to g. of a sequestering agent 60 to 100 g. of trisodium phosphate 35to 50 g. of an alkali metal sulfite 0.1 to l g. of a stabilizer, such aspotassium bromide 10 to 100 mg. of a polyalcohol or polyamine water upto l 1.

Other additives such as agents for preventing or reducing the formationof sludge of silver of silver compounds may, of course, also be added tothe activator bath.

Other silver salt solvents such as sodium thiosulfate may also be usedin quantities of about 5 to 75 g. according to the particular kind ofsilver salt diffusion process which is being used. The quantity requireddepends on whether the silver salt solvent is entirely, or partlypresent in the photographic layers.

The optimum concentration of additives for a particular purpose caneasily be determined by a few simple tests customarily employed in theart.

The light-sensitive photographic materials suitable for the inventionhave the usual composition. They contain at least one supported silverhalide emulsion layer preferably on a paper support. The silver halidesused may be silver chloride,

silver bromide or mixtures of these silver halides, if desired togetherwith small quantities of silver iodide of up to 10 mols percent. Thesilver halide emulsion layer contains a photographic developersubstance.

The usual developer substances may be used, for example aromaticphenols, particularly those of the dihydroxybenzene series; furthermore,aminophenol or aminonaphthol compounds or developers of the phenylenediamine type. Developers of the 3-pyrazolidone group have proved to beparticularly suitable, in particular those of the l-phenyl-3-pyrazolidone series. l-Aryl-3-aminopyrazolines described in German Pat.No. 946,606 are also effective, especially those compounds which containan amino group attached to the aryl group. 4-aminopyrazolones asmentioned in German Pat. No. 955,025 are also suitable.

So-called masked photographic developers are particularly useful. lnthese developers, photographically active groups are rendered inactiveby substituents which are split off before development. Thelight-sensitive layers are therefore very stable upon storage.Developers of this type have been described in German Pat. Nos.1,025,264; 1,038,913; 1,056,472; 1,159,758; 1,200,679; 1,203,129; and1,203,605 and in British Pat. No. 812,673.

In a preferred embodiment, the light-sensitive material containshydroquinone and l-phenyl-pyrazolidone-3 as developer substances.

The image receiving materials also, in principle, have the usualcomposition. They contain development nuclei for the deposition of thetransferred silver halide. These development nuclei are arranged eitherin a separate layer or in the layer support itself. Suitable nuclei arefinely divided noble metals, especially of heavy metals, e.g., silversulfide or nickel sulfide.

The image receiving layer may also be arranged on a separate support,for example, on paper or on the same support as the silver halideemulsion layer. In the latter case, both layers are on the same side ofthe support and the image receiving layer is preferably the uppermostlayer. In this case, it is advisable to arrange a white pigmentedintermediate layer between the image receiving layer and thelight-sensitive layer.

Conventional apparatus may be used for processing.

The activator baths according to the present invention are also suitablefor processing exposed silver halide emulsion layers which containdevelopers by the two-bath process (activator bath and stabilizer bath)or multibath processes (activator bath, stabilizer bath, fixing bath andwashing).

EXAMPLE 1 Image receiving material A baryta layer is applied to supportof paper g. per m?) using the following solution:

6 g. of a 50 percent aqueous slurry of barium sulfate 20 ml. of a 10percent aqueous gelatin solution 8 ml. of a 50 percent aqueous emulsionof polyvinyl acetate water up to ml.

The baryta layer is dried and then covered with an image receiving layerof the following solution (ready for casting):

4.5 g. of propylene glycol alginate 12.5 mg. of silver sulfide in theform of an aqueous colloidal solution 20 ml. of a 50 percent aqueousgelatin solution 1.5 ml. of a 30 percent aqueous solution of potassiumbromide 1.2 ml. of a 30 percent aqueous solution of saponin 7.5 g. ofsodium thiosulfate 30 mg. of the mercaptotriazole blue toner accordingto Example 1 of German Pat. No. 1,153,247 filled up with water up to 300ml.

The layer is applied in such a thickness that it contains approximately1.1 g. of sodium thiosulfate per m Another layer of the followingcasting solution is applied on the layer described above:

5.0 g. of formaldehyde bisulfite 5.0 g. of hydroquinone 3.5 g. of sodiumalginate 10 g. of sodium thiosulfate 0.8 ml. of a 30 percent aqueouspotassium bromide solution 8 ml. of a 30 percent aqueous saponinsolution made up. to

350 ml. with water.

This layer is applied in such a thickness that it contains approximately0.6 g. of sodium thiosulfate per m Light-sensitive material Alight-sensitive photographic material which has a silver chloridegelatin emulsion layer on a paper support is used. The layer has beenhardened with formaldehyde. It contains 0.8 g. of silver in the form ofsilver chloride, 850 mg. of hydroquinone and 200 mg. ofl-phenyl-pyrazolidone-B- per m Processing The image receiving layerdescribed above is brought into contact with the exposed silver chlorideemulsion layer and developed in the following activator bath in aconventional processing apparatus:

Glycerol 25 ml. Sodium thiosulfate 1.5 g. sodium sulfite anhydrous 50 g.trisodium phosphate anhydrous 30 g. l-phenyl-J-pyrazolidone 1.2 g.sodium hydroxide 1.5 g. potassium bromide l g.3-methyl-4-allyl-5-mercapto 1,2,4-triazole 30 mg. water 0.8 l,

The copies obtained when using the usual contact times of about 5 toseconds have an excellent neutral black image tone.

EXAMPLE 2 A layer of hydroxyethyl starch ether is applied to theemulsion layer to improve the contact with the image receiving layerduring processing. This layer contains 200 mg. of binder and 40 mg. ofhydroquinone per m Image receiving layer A thin gelatin layer whichcontains the following substances per m is applied on a paper support:

Gelatin 1.1 g. glycerol sulfite 1.6 g. nickel sulfide nuclei 5 mg.hydroquinone 300 mg. potassium metahisulfite 1.5 g.l-phenyl-S-mercaptotetrazole 5 mg.

Processing g The above image receiving layer 15 brought into contactwith the exposed silver chloride emulsion layer and developed in thefollowing activator bath in a conventional processing apparatus:

Trisodium phosphate 12H,O 82 g. sodium sulfite anhydrous 35 g. potassiumbromide l g. sodium thiosulfate anhydrous 7g.l-phenyl-S-mercaptotetrazole mg. ethylene diarninotetracetic acid 1 g.snrbitol made up with water to After contact times of about 10 seconds(which are customarily employed in practice) copies which have a neutralblack image tone are obtained.

We claim:

1. In a silver salt diffusion process for the production of photographicimages by exposure of a photographic material which contains at leastone supported silver halide emulsion layer, which emulsion layercontains one or more photographic developer substances, and developmentof the exposed layer by treating it with an alkaline bath in contactwith an image receiving layer which contains development nuclei, theimprovement wherein the alkaline bath contains trisodium phosphate as analkaline substance, and a polyalcohol selected from the group consistingof glycerol, mannitol and sorbitol.

2. An improved aqueous alkaline bath of the type containing trisodiumphosphate as an alkaline agent for carrying out the process according toclaim 1, wherein the improvement 0 comprises additionally containing awater-soluble aliphatic polyalcohol selected from the group consistingof glycerol, mannitol and sorbitol.

2. An improved aqueous alkaline bath of the type containing trisodiumphosphate as an alkaline agent for carrying out the process according toclaim 1, wherein the improvement comprises additionally containing awater-soluble aliphatic polyalcohol selected from the group consistingof glycerol, mannitol and sorbitol.